1. Field of the Invention
The present invention relates to a battery of a portable electronic device, and more specifically, to a verification system used for verifying authenticity of a battery used in a portable electronic device.
2. Description of the Prior Art
With the increase of portable electronic devices, batteries used to power the electronic devices have become more important. While some electronic devices use standard batteries such as AA, AAA, C, D, or 9-Volt batteries, other electronic devices make use of proprietary batteries. A common example of a portable electronic device that uses a proprietary battery is a mobile phone. Many mobile phone manufactures design their phones to operate with a proprietary battery that may have a unique size and pin layout. The manufactures of the mobile phones can then generate additional revenue from the sale of backup or replacement batteries bought for each mobile phone.
Unfortunately, the high price of proprietary batteries has created a demand for pirated batteries, and more and more batteries sold today are pirated batteries. Although pirated batteries offer a cheaper alternative to proprietary batteries, problems may arise from their use. For example, a mobile phone using a pirated battery may suffer from decreased performance, and safety becomes a bigger concern. In addition to these problems, the sale of pirated batteries also decreases the revenue of mobile phone manufactures. To combat the sale of pirated batteries, many mobile phone manufactures use piracy protection schemes in their batteries. Although the above example used mobile phones to explain the problem of battery piracy, battery piracy can potentially affect any type of portable electronic device.
Please refer to FIG. 1. FIG. 1 is a diagram of a first verification system 10 according to the prior art. In order to verify the authenticity of a battery 12, the first verification system 10 involves forming a resistor R on the battery 12 that is used in a portable electronic device 14. When the battery 12 is placed in the portable electronic device 14, the portable electronic device 14 flows a test current Ltest through the resistor R and measures a resulting voltage Vtest across the resistor R. The test current Itest, is usually produced by a fixed current source for producing a more precise resulting voltage Vtest. If the value of the resulting voltage Vtest, conforms to a predetermined voltage range in the portable electronic device 14, the battery 12 is authorized for use in the portable electronic device 14. Although the first verification system 10 is simple and inexpensive to manufacture, it is also very easy to pirate. In this case, only the single resistor R is used as an ID of the battery 12. The first verification system 10 offers little protection to battery piracy, and better protection schemes are therefore needed.
Please refer to FIG. 2. FIG. 2 is a diagram of a second verification system 20 according to the prior art. In order to verify the authenticity of a battery 22, the second verification system 20 involves serially transmitting an ID 24 of the battery 22 to a portable electronic device 30 through a single wire 28. The battery 22 contains a first controller 26 for reading the ID 24 from the battery 22 and serially transmitting the ID 24 to a second controller 32 of the portable electronic device 30. Because the first controller 26 is connected to the second controller 32 through the single wire 28, handshaking is required to establish communication between the first controller 26 and the second controller 32. Unfortunately, the handshaking mechanism used in the second verification system 20 requires using active components (the first controller 26 and the second controller 32) on both the battery 22 and the portable electronic device 30. Not only does this complicate the design of the battery 22 and the portable electronic device 30, but it also increases the manufacturing cost as well. Moreover, for all of the complexity that the second verification system 20 contains, the security lies only in the ID 24 stored in the battery 22. If this ID 24 is discovered, the battery 22 can then be pirated quite easily.